BOSTON — Colton Cowser took a walk through an iconic Fenway Park landmark on Thursday afternoon, admiring the history of the Green Monster and adding his name to the hallowed walls.

He joked that there was probably a dent in there from when he landed the night prior after making a play right at the wall. He hoped, he said, to do that again in the series finale.

That didn’t happen. But he did something even sweeter: He hit his first career home run over the very structure he was standing in earlier that day.

“That was really cool,” Cowser said. “It’s a really cool ballpark. It’s one of the ones as a kid you grow up and you just want to visit it, let alone play in it. It’s a blessing.”

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His second career home run, which came in the 10th inning, landed in right field. It padded the Orioles’ lead as they beat the Red Sox 9-4 in 10 innings to sweep their first series of the season against an American League East opponent.

For Cowser, this was a milestone to end a series in which he proved he not only can play every day but perform at the highest level.

He went 6-for-13 with 10 RBIs against the Red Sox, playing all three games in left field in place of the slumping Austin Hays. Cowser is hitting .458 with 11 RBIs, making a statement that this, not how he performed during his first stint in the majors, is what he’s capable of.

“This year I’m trying to be a little bit more confident regardless of what happens,” Cowser said. “Whether I go 0-for-4 or 4-for-4, I want to forget about it that night and go into the next day with the same mentality.”

It took time for the rest of the offense to follow Cowser’s lead, with Ryan Mountcastle and Adley Rutschman collecting the only other hits until the eighth inning. But these are, after all, the comeback kids.

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In the eighth, Jackson Holliday reached base on an error by third baseman Pablo Reyes. And, while Holliday remains hitless after his second major league game, he scored his first run after Anthony Santander homered. He also scored on a home run by Gunnar Henderson in the 10th.

It was Santander’s third home run of the season as the Orioles came from behind for the third day in a row.

Grayson Rodriguez’s night got off to a rough start, the second-year starter allowing three doubles in the first. What he proved after that first inning, though, showed a sign of his maturity. He reined in his emotions, not allowing an off first inning to hinder the rest of his outing.

He got through a 1-2-3 second and allowed only three additional hits as he pitched into the sixth.

“The first was kind of an unlucky first inning; he gave up two, but really good after that,” manager Brandon Hyde said. “I thought he was strong the second through sixth.”

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Jacob Webb took over, pitching a scoreless 1 1/3 innings. Danny Coulombe, who had yet to give up a run this season, gave up a solo home run to pinch-hitting Connor Wong, whose blast cleared the Green Monster.

Orioles starter Grayson Rodriguez allowed two runs, both in the first inning, in 5 2/3 innings against the Red Sox. (Paul Rutherford/Getty Images)

In the top of the ninth, Cedric Mullins and Jordan Westburg walked. The Orioles’ dugout stood on the top step as Holliday stepped to the plate with two outs in a tie game.

This could have been his moment, his chance to get his first hit in a signature moment. Instead, he struck out and the game remained tied.

After Craig Kimbrel shut down his former team in the bottom of the ninth, the Orioles and Red Sox went to extras.

Henderson quickly put an end to things. With Holliday stationed as the ghost runner on second, Henderson hit a home run to open the 10th to give the Orioles back the lead. Then Mullins added one more, hitting an RBI single to make it 6-3.

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They weren’t done there, though. On a 3-0 count, Cowser made sure the game was extra secure, hitting a three-run homer.

“That was awesome,” Henderson said. “He’s just showing what he can do, He’s a really awesome player, and I’m really happy for him.”

Now the Orioles will head home, only a little later than they anticipated, where Baltimore will formally get introduced to Holliday on Friday in his Camden Yards debut.

Danielle Allentuck covers the Orioles for The Baltimore Banner. She previously reported on the Rockies for the Denver Gazette and general sports assignments for The New York Times as part of its fellowship program. A Maryland native, Danielle grew up in Montgomery County and graduated from Ithaca College.

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